var arr = [20,60,21,35,70];

for (var i = 0;i<arr.length;i++)
{
    for(var j = 0;j<arr.length;j++)
    {
        if(arr[j]>arr[j+1])
        {
            var temp = arr[j];
            arr[j] = arr[j + 1];
            arr[j + 1] = temp
        }
    }
}

console.log(arr);